Ready-to-use hot melt adhesive having an improved property profile

ABSTRACT

The invention relates to a ready-to-use hot melt adhesive containing at least 95% of one or more polyolefin copolymer waxes, which have been prepared by means of metallocene catalysts, characterized in that the polyolefin copolymer wax consists of propylene and one or more further monomers selected from ethylene and branched or unbranched 1-alkenes having 4 to 20 C-atoms and the content of structural units derived from propylene in the copolymer waxes amounts to 80 to 99.9% by weight, and the hot melt adhesive has a surface tension of the melt, measured at a temperature of 170 DEG C., of at most 23 mN/m. The invention relates to a ready-to-use hot melt adhesive containing at least 95% of one or more polyolefin copolymer waxes, which have been prepared by means of metallocene catalysts, characterized in that the polyolefin copolymer wax consists of propylene and one or more further monomers selected from ethylene and branched or unbranched 1-alkenes having 4 to 20 C-atoms and the content of structural units derived from propylene in the copolymer waxes amounts to 80 to 99.9% by weight, and the hot melt adhesive has a surface tension of the melt, measured at a temperature of 170 DEG C., of at most 23 mN/m. The invention relates to a ready-to-use hot melt adhesive containing at least 95% of one or more polyolefin copolymer waxes, which have been prepared by means of metallocene catalysts, characterized in that the polyolefin copolymer wax consists of propylene and one or more further monomers selected from ethylene and branched or unbranched 1-alkenes having 4 to 20 C-atoms and the content of structural units derived from propylene in the copolymer waxes amounts to 80 to 99.9% by weight, and the hot melt adhesive has a surface tension of the melt, measured at a temperature of 170 DEG C., of at most 23 mN/m. The invention relates to a ready-to-use hot melt adhesive containing at least 95% of one or more polyolefin copolymer waxes, which have been prepared by means of metallocene catalysts, characterized in that the polyolefin copolymer wax consists of propylene and one or more further monomers selected from ethylene and branched or unbranched 1-alkenes having 4 to 20 C-atoms and the content of structural units derived from propylene in the copolymer waxes amounts to 80 to 99.9% by weight, and the hot melt adhesive has a surface tension of the melt, measured at a temperature of 170 DEG C., of at most 23 mN/m.

The invention relates to ready-to-use hotmelt adhesives having animproved spectrum of properties (heat distortion resistance, cohesion,adhesion, low VOC, open time), consisting of polyolefin waxes producedusing metallocene catalysts.

Hotmelt adhesives or hotmelts are thermoplastic materials which aresolid at ambient temperature, and are applied in the liquid-melt state,as strands or layers, to suitable substrate surfaces, where theysolidify and then exert different functions. They are constructedpreferably on the basis of resins, waxes, thermoplastic polymers, andelastomers, and optionally include additions of fillers, pigments, andadditives such as stabilizers, etc.

Hotmelt adhesives may be used, for example, as solvent-free adhesivesfor bonding. Melt adhesives of this kind are increasingly being used,for their diverse advantages, in industries including packaging,furniture, textiles, and footwear, as an economical and eco-friendlyalternative to conventional, solvent-based adhesives. Ingredients oftypical melt adhesive formulas are polar or apolar polymers, generallyethylene vinyl acetate copolymers; resins; and waxes.

The polar or apolar polymers in these formulas serve as scaffoldmaterial. They ensure the cohesion of the adhesive and at the same timecontribute to adhesion to the substrate. The resin addition improves theadhesion effect and may possibly exert a compatibilizing effect on thevarious components of the adhesive. Waxes are used for modification infractions of generally less than 10 wt %, based on the melt adhesivecompositions. They regulate important physical properties of theadhesives such as, for instance, hardness, melt viscosity, and softeningpoint, and critically influence the performance behavior through theireffect on open time, adhesion, cohesion, etc. Employed in quantities ofmore than 10 wt %, waxes have hitherto been found in general to impairthe properties, and more particularly to diminish the bond strength ofthe hotmelt adhesive.

Waxes employed hitherto in hotmelt adhesives have been macrocrystallineand microcrystalline paraffin waxes, Fischer-Tropsch waxes, andpolyolefin waxes. Polyolefin waxes, in delimitation from plastics, referhere to those polyolefins whose melt viscosity at 170° C. is below 40000 mPa·s.

Polyolefin waxes may be produced by thermal degradation of branched,high-polymer polyolefin plastics, or by direct polymerization ofolefins. Examples of suitable polymerization methods includehigh-pressure technologies, in which the olefins, generally ethylene,are reacted by a radical mechanism at high pressures and temperatures toform branched waxes. Besides this there is the low-pressure or Zieglermethod, in which ethylene and/or higher 1-olefins are polymerized attemperatures and pressures which are lower by comparison, with the aidof organometallic catalysts.

Disclosed more recently, as a variant of the low-pressure method, is aprocedure wherein metallocene compounds are used as organometalliccatalysts. These compounds comprise complexes of titanium, of zirconium,or of hafnium as active species, and are employed generally incombination with cocatalysts, examples being organoaluminum compounds orboron compounds, preferably aluminoxane compounds. The polymerizationtakes place where necessary in the presence of hydrogen as an agentregulating molar mass. A feature of metallocene processes is that incomparison with the older Ziegler technology, it is possible to obtainwaxes with a narrower molar mass distribution, uniform comonomerincorporation, defined tacticity (e.g., a-, iso-, syndio-, hemiiso-,etc.), lower melting points, and greater catalyst effectiveness.

Melt adhesive mixtures based on abovementioned components (polymer,resin, wax, etc.), especially based on metallocene-catalyzedpolyolefins, are known and are already long-established state of theart. Thus, for example, EP1631641 uses polyolefin waxes produced bymetallocene catalysis, as a minority-amount component, in melt adhesivemixtures which comprise EVA polymers and hydrocarbon resins as furtherconstituents. EP1645608 describes melt adhesive mixtures whose scaffoldsubstance, and hence more than 50 wt %, is based on a polyolefincopolymer produced by metallocene methods, but which in the embodimentsdescribed include hydrocarbon resins as a further constituent. EP2081609describes the use of melt adhesive mixtures of this kind for the bondingof textile fibers to one another and/or to other smooth substrates inhygiene articles.

There is increasingly a desire, as is known, to obtain melt adhesiveswithout prior compounding of the individual components. This impliesthat the matrix material unites the functions of resin, wax, and carrierpolymer in one substance. This is desirable both for reasons ofsimplification in production (reduced complexity) of such meltadhesives, and also from the standpoint of environmental compatibilityand climate compatibility, through avoidance of unnecessaryenergy-intensive process steps. EP1645608B1, with a polyolefin waxfraction of >50 wt %, in fact also implies hotmelt adhesives constructedexclusively as one-component systems; however, a suitable one-componentembodiment is not described, and nor does the patent specificationprovide the skilled person with information as to how to produce anysuch property-combining polyolefin wax and how to carry out selectionaccordingly, nor how best to compensate the loss of adhesion throughomission of a resin.

It has surprisingly been found that a ready-to-use hotmelt compositionconsisting exclusively of reactor-ready polyolefin waxes produced usingmetallocene catalysts and having a number-average molar mass of 15000-25 000 g/mol and a weight-average molar mass of 25 000 to 35 000g/mol, a dropping point or ring & ball softening point of between 100and 120° C., a melt viscosity, measured at a temperature of 170° C., ofbetween 8000 and 15 000 mPa·s, a glass transition temperature of notmore than −15° C., and a surface tension at 170° C. of more than 23 mN/mare suitable with particular advantage as one-component hotmeltadhesives. One-component hotmelt adhesives of this kind require nofurther energy-intensive compounding, and within the polyolefin waxesare notable for improved cohesion, reduced open time, improved heatdistortion resistance and low-temperature flexibility, and hence abroader application spectrum. Such one-component hotmelt adhesives aretherefore especially suitable for the bonding and laminating ofsheetlike textile structures (carpets, mattress covers, spring pockets)and particularly in the context of bonding of low surface energysubstrates (e.g., PE, PP, etc.). It has been found, moreover, thatone-component hotmelt adhesives of these kinds have a particularly lowfraction of volatile organic compounds (low VOC).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph showing the determination of thetemperatue/application spectrum ΔT_(entropy-el) from the δ_(max) and tanδ_(onset) for melt adhesive 3.

DESCRIPTION

The invention accordingly provides ready-to-use hotmelt adhesivescomprising at least 95 wt % of one or more polyolefin waxes producedusing metallocene catalysts, the polyolefin copolymer wax consisting ofpropylene and one or more further monomers selected from ethylene andbranched or unbranched 1-alkenes having 4 to 20 C atoms, and the amountof structural units originating from propylene in the copolymer waxesbeing 80 to 99.9 wt %, and the hotmelt adhesive having a melt surfacetension, measured at a temperature of 170° C., of not more than 23 mN/m.

The term “ready-to-use” means in this context that a separatelysubsequent compounding step after the process of polymerizing thepolyolefin waxes of the invention, for the purpose of mixing with othercomponent materials, such as mixing with resin, carrier polymer or wax,for example, is explicitly excluded. Customary additization withminority-amount components add up to a maximum of 5 wt %, preferably upto a maximum of 2 wt %, more preferably a maximum of 0.5 wt %, incontrast, is not excluded, provided it takes place in conjunction withshaping (finishing) after the polymerization process. The term“one-component” refers here to the class of polyolefin wax materials,and therefore implies inter alia, for example, reactor blends ofdifferent polyolefin waxes, whereas mixtures of EVA and polyolefin waxand of resin and polyolefin wax should be understood as multicomponentsystems not in accordance with the invention.

Suitable polyolefin waxes present in the ready-to-use hotmelt adhesivesof the invention include, for example, copolymers of propylene withethylene and/or with higher 1-olefins or copolymers thereof. Higher1-olefins used are preferably linear or branched olefins having 4 to 20C atoms and preferably having 4 to 6 C atoms. Examples of these are1-butene, 1-hexene, 1-octene, or 1-octadecene. The copolymers consist ofone kind of olefin to an extent of preferably 80 to 99.9 and morepreferably 85 to 95 wt %.

In one preferred embodiment the copolymers of the ready-to-use hotmeltadhesives of the invention consist of 85 to 95 wt % propylene and 5-15wt % ethylene.

With preference, copolymers used in accordance with the invention in theready-to-use hotmelt adhesives of the invention have a melt surfacetension, measured at a temperature of 170° C., of not more than 23 mN/m,preferably of not more than 22.5 mN/m.

The polyolefin waxes present in the ready-to-use hotmelt adhesives ofthe invention preferably have a number-average molar mass M_(n) ofbetween 15 000 and 25 000 g/mol, more preferably between 17 000 and 22000 g/mol, and preferably have a weight-average molar mass M_(w) ofbetween 25 000 and 35 000 g/mol, more preferably between 28 000 and 32000 g/mol.

The polyolefin waxes present in the ready-to-use hotmelt adhesives ofthe invention have a dropping point or ring & ball softening point ofbetween 100 and 120° C., preferably between 110 and 120° C., a heat offusion of 0 to 60 J/g, preferably between 40 and 60 J/g, a meltviscosity, measured at a temperature of 170° C., of between 8000 and 15000 mPa·s, preferably between 8000 and 11 000 mPa·s, and a glasstransition temperature (DSC) of not more than −15° C., preferably notmore than −20° C.

Polyolefin waxes used in accordance with the invention are preparedusing metallocene compounds of the formula (I).

This formula also embraces compounds of the formula (Ia),

of the formula (Ib)

and of the formula (Ic)

In the formulae (I), (Ia), and (Ib), M¹ is a metal from group IVb, Vb,or VIb of the Periodic Table, as for example titanium, zirconium,hafnium, vanadium, niobium, tantalum, chromium, molybdenum, or tungsten,preferably titanium, zirconium, or hafnium.

R¹ and R² are identical or different and are a hydrogen atom, a C₁-C₁₀,preferably C₁-C₃ alkyl group, more particularly methyl, a C₁-C₁₀,preferably C₁-C₃ alkoxy group, a C₆-C₁₀, preferably C₆-C₈ aryl group, aC₆-C₁₀, preferably C₆-C₈ aryloxy group, a C₂-C₁₀, preferably C₂-C₄alkenyl group, a C₇-C₄₀, preferably C₇-C₁₀ arylalkyl group, a C₇-C₄₀,preferably C₇-C₁₂ alkylaryl group, a C₈-C₄₀, preferably C₈-C₁₂arylalkenyl group, or a halogen, preferably chlorine atom.

R³ and R⁴ are identical or different and are a mono- or polycyclichydrocarbon radical, which may form a sandwich structure with thecentral atom M¹. Preferably R³ and R⁴ are cyclopentadienyl, indenyl,tetrahydroindenyl, benzoindenyl, or fluorenyl, and the parent structuresmay further carry additional substituents or be bridged with oneanother. Moreover, one of the radicals R³ and R⁴ may be a substitutednitrogen atom, with R²⁴ having the definition of R¹⁷ and beingpreferably methyl, tert-butyl or cyclohexyl.

R⁵, R⁶, R⁷, R⁸, R⁹, and R¹⁰ are identical or different and are ahydrogen atom, a halogen atom, preferably a fluorine, chlorine, orbromine atom, a C₁-C₁₀, preferably C₁-C₄ alkyl group, a C₆-C₁₀,preferably C₆-C₈ aryl group, a C₁-C₁₀, preferably C₁-C₃ alkoxy group, aradical —NR¹⁶ ₂—, —SR¹⁶—, —OSiR¹⁶ ₃—, —SiR¹⁶ ₃—, or

—PR¹⁶ ₂, in which R¹⁶ is a C₁-C₁₀, preferably C₁-C₃ alkyl group orC₆-C₁₀, preferably C₆-C₈ aryl group or else, in the case of radicalscontaining Si or P, is a halogen atom, preferably chlorine atom, or twoadjacent radicals R⁵, R⁶, R⁷, R⁸, R⁹, or R¹⁰ form a ring with the Catoms connecting them. Particularly preferred ligands are thesubstituted compounds of the parent structures cyclopentadienyl,indenyl, tetrahydroindenyl, benzoindenyl or fluorenyl.

R¹³ is

═BR¹⁷, ═AlR¹⁷, —Ge—, —Sn—, —O—, —S—, ═SO, ═SO₂, ═NR¹⁷, ═CO, ═PR¹⁷ or═P(O)R¹⁷, with R¹⁷, R¹⁸, and R¹⁹ being identical or different and beinga hydrogen atom, a halogen atom, preferably a fluorine, chlorine, orbromine atom, a C₁-C₃₀, preferably C₁-C₄ alkyl group, more particularlymethyl group, a C₁-C₁₀ fluoroalkyl, preferably CF₃ group, a C₆-C₁₀fluoroaryl, preferably pentafluorophenyl group, a C₆-C₁₀, preferablyC₆-C₈ aryl group, a C₁-C₁₀, preferably C₁-C₄ alkoxy group, moreparticularly methoxy group, a C₂-C₁₀, preferably C₂-C₄ alkenyl group, aC₇-C₄₀, preferably C₇-C₁₀ aralkyl group, a C₈-C₄₀, preferably C₈-C₁₂arylalkenyl group, or a C₇-C₄₀, preferably C₇-C₁₂ alkylaryl group, orR¹⁷ and R¹⁸ or R¹⁷ and R¹⁹ form a ring in each case together with theatoms connecting them.

M² is silicon, germanium, or tin, preferably silicon and germanium. R¹³is preferably ═CR¹⁷R¹⁸, ═SiR¹⁷R¹⁸, ═GeR¹⁷R¹⁸, —O—, —S—, ═SO, ═PR¹⁷, or═P(O)R¹⁷.

R¹¹ and R¹² are identical or different and have the definitions statedfor R¹⁷.

m and n are identical or different and are zero, 1, or 2, preferablyzero or 1, with m plus n being zero, 1, or 2, preferably zero or 1.

R¹⁴ and R¹⁵ have the definition of R¹⁷ and R¹⁸.

Examples of suitable metallocenes are as follows:

-   bis(1,2,3-trimethylcyclopentadienyl)zirconium dichloride,-   bis(1,2,4-trimethylcyclopentadienyl)zirconium dichloride,-   bis(1,2-dimethylcyclopentadienyl)zirconium dichloride,-   bis(1,3-dimethylcyclopentadienyl)zirconium dichloride,-   bis(1-methylindenyl)zirconium dichloride,-   bis(1-n-butyl-3-methyl-cyclopentadienyl)zirconium dichloride,-   bis(2-methyl-4,6-diisopropylindenyl)zirconium dichloride,-   bis(2-methylindenyl)zirconium dichloride,-   bis(4-methylindenyl)zirconium dichloride,-   bis(5-methylindenyl)zirconium dichloride,-   bis(alkylcyclopentadienyl)zirconium dichloride,-   bis(alkylindenyl)zirconium dichloride,-   bis(cyclopentadienyl)zirconium dichloride,-   bis(indenyl)zirconium dichloride,-   bis(methylcyclopentadienyl)zirconium dichloride,-   bis(n-butylcyclopentadienyl)zirconium dichloride,-   bis(octadecylcyclopentadienyl)zirconium dichloride,-   bis(pentamethylcyclopentadienyl)zirconium dichloride,-   bis(trimethylsilylcyclopentadienyl)zirconium dichloride,-   biscyclopentadienylzirconium dibenzyl,-   biscyclopentadienylzirconium dimethyl,-   bistetrahydroindenylzirconium dichloride,-   dimethylsilyl-9-fluorenylcyclopentadienylzirconium dichloride,-   dimethylsilylbis-1-(2,3,5-trimethylcyclopentadienyl)zirconium    dichloride,-   dimethylsilylbis-1-(2,4-dimethylcyclopentadienyl)zirconium    dichloride,-   dimethylsilylbis-1-(2-methyl-4,5-benzoindenyl)zirconium dichloride,-   dimethylsilylbis-1-(2-methyl-4-ethylindenyl)zirconium dichloride,-   dimethylsilylbis-1-(2-methyl-4-isopropylindenyl)zirconium    dichloride,-   dimethylsilylbis-1-(2-methyl-4-phenylindenyl)zirconium dichloride,-   dimethylsilylbis-1-(2-methylindenyl)zirconium dichloride,-   dimethylsilylbis-1-(2-methyltetrahydroindenyl)zirconium dichloride,-   dimethylsilylbis-1-indenylzirconium dichloride,-   dimethylsilylbis-1-indenylzirconium dimethyl,-   dimethylsilylbis-1-tetrahydroindenylzirconium dichloride,-   diphenylmethylene-9-fluorenylcyclopentadienylzirconium dichloride,-   diphenylsilylbis-1-indenylzirconium dichloride,-   ethylenebis-1-(2-methyl-4,5-benzoindenyl)zirconium dichloride,-   ethylenebis-1-(2-methyl-4-phenylindenyl)zirconium dichloride,-   ethylenebis-1-(2-methyl-tetrahydroindenyl)zirconium dichloride,-   ethylenebis-1-(4,7-dimethylindenyl)zirconium dichloride,-   ethylenebis-1-indenylzirconium dichloride,-   ethylenebis-1-tetrahydroindenylzirconium dichloride,-   indenylcyclopentadienylzirconium dichloride-   isopropylidene(1-indenyl)(cyclopentadienyl)zirconium dichloride,-   isopropylidene(9-fluorenyl)(cyclopentadienyl)zirconium dichloride,-   phenylmethylsilylbis-1-(2-methylindenyl)zirconium dichloride,-   and also in each case the alkyl or aryl derivatives of these    metallocene dichlorides.

The single-center catalyst systems are activated using suitablecocatalysts.

Suitable cocatalysts for metallocenes of the formula (I) areorganoaluminum compounds, more particularly aluminoxanes, or elsealuminum-free systems such as R²⁰ _(x)NH_(4-x)BR²¹ ₄, R²⁰_(x)PH_(4-x)BR²¹ ₄, R²⁰ ₃CBR²¹ ₄, or BR²¹ ₃. In these formulae, x is anumber from 1 to 4, the radicals R²⁰ are identical or different,preferably identical, and are C₁-C₁₀ alkyl or C₆-C₁₈ aryl, or tworadicals R²⁰ form a ring together with the atom connecting them, and theradicals R²¹ are identical or different, preferably identical, and areC₆-C₁₈ aryl, which may be substituted by alkyl, haloalkyl, or fluoro.More particularly, R²⁰ is ethyl, propyl, butyl or phenyl, and R²¹ isphenyl, pentafluorophenyl, 3,5-bistrifluoromethylphenyl, mesityl, xylylor tolyl.

Additionally a third component is often necessary in order to maintainprotection from polar catalyst poisons. Suitable for this purpose areorganoaluminum compound such as, for example, triethylaluminum,tributylaluminum, and others, and also mixtures.

Depending on process, supported single-center catalysts may also beused. Preferred catalyst systems are those in which the residual amountsof support material and cocatalyst do not exceed a concentration of 100ppm in the product.

In the case of processes described above, the use of mixtures ofsingle-center catalysts with different stereoselectivites and/ordifferent activities, in supported and also unsupported form, is alsopossible. The products produced in the case of a process variant of thiskind are referred to as reactor blends. The polymers obtained in thecase of this process variant are considered a uniform class of material,owing to the identity of monomer building blocks, and therefore asone-component systems. The polyolefin waxes of the invention thereforealso include reactor blends. In the present invention these aremetallocene-based polyolefin waxes, more particularly ethylene-propylenecopolymers, for example.

The ethylene-propylene-based copolymer waxes produced by processesdescribed above have a profile of properties which is particularlyadvantageous for the ready-to-use hotmelt adhesives of the invention.The advantageous profile of properties includes the following: highcohesion, without being brittle in the application; a broadtemperature/application spectrum, limited at the bottom end by glasstransition temperature and at the top end by softening temperature; amelt surface tension at 170° C.<23 mN/m for improved wetting,particularly of low surface energy surfaces, such as polyolefinsurfaces, for example; a short open time, for high working speeds.

The present invention therefore provides ready-to-use one-componenthotmelt adhesives based on polyolefin waxes produced by metallocenecatalysis. In terms of its physical and chemical properties, theready-to-use one-component hotmelt adhesive preferably correspondsexactly to the polyolefin wax or to the polyolefin wax reactor blend.

The ready-to-use hotmelt adhesives of the invention preferably have adropping point or ring & ball softening point of between 100 and 120°C., a melt viscosity, measured at a temperature of 170° C., of between8000 and 15 000 mPa·s, a glass transition temperature (DSC) of not morethan −15° C., and a melt surface tension, measured at a temperature of170° C., of not more than 23 mN/m.

The ready-to-use hotmelt adhesives of the invention more preferably havea dropping point or ring & ball softening point of between 110 and 120°C., a melt viscosity, measured at a temperature of 170° C., of between8000 and 11 000 mPa·s, a glass transition temperature (DSC) of not morethan −20° C., and a melt surface tension, measured at a temperature of170° C., of not more than 23 mN/m.

In accordance with the invention the ready-to-use hotmelt adhesives arenotable for a particularly broad temperature/application spectrum bycomparison with EVA-based melt adhesives. For the ready-to-use hotmeltadhesives, this is manifested in an entropy-elastic range from 80 to110° C. The entropy-elastic range ΔT_(entropy-el) (tan δ) is determinedfrom the difference of the maximum for the loss factor tan δ_(max) andthe softening point in the DMA (onset of the loss factor tan δ_(onset)).The loss modulus profile is measured by means of DMA measurement inaccordance with DIN ISO 6721-1. The maximum of the loss factor tanδ_(max) is determined according to ASTM D 4065-99, while the onset ofthe loss factor at the softening point is determined by way of thetangent method (see FIG. 1).

The ready-to-use hotmelt adhesives of the invention may further comprisepolyolefin polymers, resins, waxes, plasticizers, polar or apolarpolymers, pigments, fillers, stabilizers and/or antioxidants incustomary additive concentrations.

Further provided by the invention is the use of the ready-to-use hotmeltadhesives of the invention as melt adhesives. The ready-to-use hotmeltadhesives consist preferably to an extent of 95 to 100 wt %, morepreferably 98 to 100 wt %, very preferably 99 to 100 wt %, of thepolyolefin waxes described above.

The ready-to-use hotmelt adhesive of the invention finds use in thebonding, laminating, fixing, and coating of sheetlike structures of anykind, such as carpet reverse-face coating, artificial turf reverse-facecoating, adhesive bonding of spring pockets (mattresses), nonwovens, orof nonwoven-web materials. The ready-to-use hotmelt adhesive of theinvention is also suitable for producing any of a very wide variety ofhygiene articles, such as diapers, training pants, incontinenceproducts, panty liners, and sanitary towels, more particularly for thelaminating of fiber materials such as nonwoven-web materials with film.

In view of the improved mechanical properties, the ready-to-use hotmeltadhesive of the invention can also be used as a binder for theproduction of road surfacing.

The ready-to-use hotmelt adhesive of the invention is suitable withparticular advantage for the bonding, laminating, and fixing ofsubstrates with a total surface energy of γ_(tot)<30 mN/m, referred toas low surface energy substrates. These include, in particular,polypropylene and polyethylene. Such substrates preferably have a lowpolar component γ_(P)<2 mN/m in the total surface energy. The latter isobtained from the sum of the polar and disperse surface energycomponents: γ_(tot)=γ_(p)+γ_(d)

The examples which follow are intended to elucidate the invention inmore detail, but without confining it to them.

EXAMPLES

p The melt viscosities were determined according to DIN 53019 with arotary viscometer, the dropping points according to DIN 51801/2, thering & ball softening point according to DIN EN 1427. The glasstransition temperatures and also the enthalpies of fusion weredetermined by means of differential thermal analysis according to DIN ENISO 11357-1 from −50 to 200° C. at a heating rate of 10 K/min undernitrogen.

The molar mass weight average M_(w), the molar mass number averageM_(n), and the resulting quotient M_(n)/M_(w) (PDI) were determined bygel permeation chromatography at 135° C. in 1,2-dichlorobenzene withreference to a PP standard.

The surface tension of the hotmelt adhesives and of the polyolefin waxesis determined by means of the “pendant drop” method, with the aid of aheated measurement chamber and of a heated ceramic needle at 170° C.

The melt densities required for this measurement were determinedlikewise at 170° C.

The volatility was determined by thermogravimetry via TGA measurementsunder nitrogen. For this purpose, around 10 mg of sample were heated to300° C. at a heating rate of 5 K/min, and the loss in mass was recorded.The measurement was made under a nitrogen atmosphere with an N₂ flowrate of 50 ml/min.

The metallocene-polyolefin waxes listed in table 1 were produced by theprocesses indicated in EP-A-0 571 882. For a given catalyst system andgiven comonomer ratio, the molecular weight was regulated via thehydrogen partial pressure as molar mass regulator.

Examples 1-13 show a selection of typical ethylene-propylene basedcopolymer waxes and their profile of properties (melt viscosity, EWP,surface tension, enthalpy of fusion, glass transition temperature),sorted according to ascending softening temperature. In the subsequentapplication as melt adhesives, the softening temperature has a directinfluence on the heat distortion resistance and hence on the maximumservice temperature after bonding has taken place. The glass transitiontemperature has a direct influence on the low-temperature flexibility ofan adhesive bond. In addition, the enthalpy of fusion (as a measure ofthe crystallinity) limits the toughness and cohesion of the adhesivematerial after bonding. Melt viscosity and melt surface tension, incontrast, are significant for the applicability of the liquid meltadhesive. A low surface tension here leads to more effective wetting ofthe surface.

Examples 5, 6, 9, 10, and 11, with a constant propylene content of 89 wt% and 11 wt % ethylene, show a change in the profile of properties withincreasing molecular weight. The molecular weight here was controlled byway of the hydrogen partial pressure during the polymerization.Accordingly, the increase in the molecular weight leads to an increasein the melt viscosity, in the softening point, in the crystallinity inthe form of the enthalpy of fusion, and in the melt surface tension. Atthe same time there is a decrease in volatility with increasingmolecular weight.

TABLE 1 Properties of various ethylene-propylene polyolefin copolymerwaxes Melt Glass transition Surface Propylene Heat of viscositytemperature tension Volatility content SFP fusion DSC M_(w) M_(n) 170°C. DSC 170° C. TGA Example [wt %] [° C.] [J/g] [g/mol] [g/mol] PDI[mPas] [° C.] [mN/m] [%@300° C.]  1 (comp.) 90 86 31 22 100 13 300 1.71800 −28 21.6 0.5  2 (comp.) 91 88 30 29 700 18 500 1.6 7000 −26 23.10.1  3 (comp.) 90 90 36   8700   6000 1.5 200 −30 20.8 0.7  4 (comp.) 9952 22 300 13 100 1.7 1500 −24 21.5 0.5  5 (comp.) 89 100 46 29 700 17900 1.7 6300 −24 22.5 0.2  6 (comp.) 89 103 44 26 300 14 600 1.8 7800−21 21.8 0.5  7 (comp.) 107   8800   5200 1.7 1300 n.b. n.b. n.b.  8(comp.) 108 44 19 800   7900 2.5 2300 n.b. 22.9 n.b.  9 (inv.) 89 117 5430 800 20 700 1.5 8900 −20 21.9 0.1 10 (comp.) 89 120 64 32 300 21 7001.5 9200 −20 22.2 0.2 11 (comp.) 89 135 77 35 300 22 800 1.5 9500 n.b0.1 12 (comp.) 48 60 −25 n.b. 1.1 13 (comp.) 100 145 108   7200   46001.6 60 n.a. 19.5 2.6 n.b. not determined n.a. not determinable SFP:softening point

The intention below is to show that the ethylene-propylene copolymer waxof the invention (example 5) fulfills, in a particularly suitable way,the performance requirements of a ready-to-use melt adhesive in thesense according to the invention.

A. Use in Melt Adhesive Formulas

Using the waxes listed in table 1, melt adhesive compositions wereproduced according to the mixing ratios set out in table 2. Thecomponents were jointly melted and stirred at 180° C. for 1 hour.

To test the cohesion, moldings were made from the mixtures in accordancewith DIN 53455, and the mechanical stability of these moldings wastested in a tensile test.

The temperature/application spectrum was determined by way of theentropy-elastic range ΔT_(entropy-el) (tan δ) and is obtained from thedifference of the maximum of the loss factor (tan δ_(max)) and the onsetof the loss factor (tan δ_(onset)): ΔT_(entropy-el)=T(tanδ_(onset))−T(tan δ_(max)). The loss factor was determined by DMAmeasurement according to DIN ISO 6721-1. The maximum of the loss factor(tan δ_(max)) was determined according to ASTM D 4065-99, while theonset of the loss factor at the softening point was determined via thetangent method (see FIG. 1). The heating rate for the DMA measurementwas 3 K/min, the amplitude 20 μm, and the measurement frequency 1 Hz.The molded specimen geometry was always 2 mm×3.5 mm×12.82 mm.

The open time was determined after melting of the melt adhesivecompositions set out in table 2, at 140° C., for a 500 μm film of meltknife-coated on an uncoated cardboard surface. In addition, withinseconds, paper strips (1 cm×5 cm) were pressed onto the film of melt asit cooled. Following complete hardening of the melt adhesive, the paperstrips are peeled off. When there is no complete fiber extraction at thebond site, the end of the open time has been reached.

The application-relevant determination of the maximum pull strength ofthe bond between two pockets of a pocket-sprung mattress, and hence ofthe adhesion, was made using mechanically bonded spring pockets by atensile test in analogy to ASTM D751. For this purpose, an area of 10cm×10 cm of the bonded pockets was cut out at the bond face and measuredunder tension. The pocket material consisted of a PP-based nonwoven.

TABLE 2 Melt adhesives and formula mixtures for application Wax Wax WaxWax Wax ex 9 Wax Licocene ® EVA Melt ex 1 ex 2 ex 5 ex 6 (inv.) ex 10Elvax ® 220 APAO Resin PE 4201 hotmelt adhesive [wt %] [wt %] [wt %] [wt%] [wt %] [wt %] [wt %] [wt %] [wt %] [wt %] Forbo  1 (comp.) 100 — — —— — — — — — —  2 (comp.) — 100 — — — — — — — — —  3 (comp.) — — 100  — —— — — — — —  4 (comp.) — — — 100 — — — — — — —  5 (inv.) — — — — 100 — —— — — —  6 (comp.) — — — — — 100 — — — — —  7 (comp.) — — — — — — 100 —— — —  8 (comp.) — — — — — — — 100 — — —  9 (inv.) — — — —  96 — — — 4 —— 10 (inv.) — — — — — —  96 — 4 — — 11 (comp.) — — 97 — — — — — — 3 — 12(comp.) — — 94 — — — — — — 6 — 13 (comp.) — — — — — — — — — — 100Elvax ® 220: ethylene-vinyl acetate copolymer, manufacturer Dupont AGRegalite ® 1140: hydrocarbon resin, manufacturer Eastman Licocene ® PE4201: polyethylene wax Forbo: EVA hotmelt (consisting of resin, EVA)n.b. not determined n.a. not determinable SFP: softening point

TABLE 3 Peformance-relevant properties of reactor-ready melt adhesivesin the examples: bonding of the pockets of pocket- sprung mattresses,and reverse-face coating of artificial turf. Glass Pull Flexibility Melttransition ΔT_(entropy-el) Surface Open strength during roll-upviscosity temperature (temperature/ tension time between of coated Melt170° C. DSC SFP application 170° C. Cohesion 140° C. 2 pocketsartificial turf adhesive [mPas] [° C.] [° C.] spectrum) [mN/m] [N/mm²][s] [N] [qualitative]  1 (comp.) E,P 1800 −28 86 88 21.6 3.2 50 does notcopolymer rupture  2 (comp.) E,P 7000 −26 88 83 23.1 4.9 70 does notcopolymer rupture  3 (comp.) E,P 6300 −24 100 82 22.5 9.3 35 77 does notcopolymer rupture  4 (comp.) E,P 7800 −21 103 84 21.8 10.5 15 does notcopolymer rupture  5 (inv.) E,P 8900 −20 117 101 21.9 16.7 5 88 does notcopolymer rupture  6 (comp.) E,P 9200 −20 120 103 22.2 18.3 2 rupturescopolymer  7 (comp.) EVA >100000 −34 70 76 7.5 35 does not rupture  8(comp.) APAO 4000 −28 +124 89 1.0 18 does not rupture  9 (inv.) E,P 9600−18 116 99 16.4 7 89 does not copolymer + rupture resin 10 (comp.) EVA +resin 93300 −32 70 73 7.4 55 does not rupture 11 (comp.) E,P- 5600 −22124 91 23.3 8.9 10 does not copolymer + rupture ethylene wax 12 (comp.)E,P 5000 −21 126 3 22.9 7.4 5 does not copolymer + rupture ethylene wax13 (comp.) EVA 4000 83 49 6 76 does not hotmelt rupture

Melt adhesives 5 and 9 fulfill the profile of properties according tothe invention for a ready-to-use melt adhesive, with atemperature/application spectrum, broad in the inventive sense, with ashort open time, and with a high melt adhesive cohesion. The meltsurface tension <23 mN/m at 170° C. suggests effective wetting of thesurface to be bonded. Comparative examples 1-4, 6-8, and 10-13 fail tomeet the required profile of properties in at least one property (opentime, toughness, strength, flexibility, temperature/applicationspectrum).

The examples for the ethylene-propylene polyolefin copolymer waxes intable 1 and table 3 show that an increase in the softening point andhence in the distortion resistance usually correlates with an increasein the crystallinity and at the same time with the loss of theflexibility. This problem has been counterable to date only bycorresponding compounding. Melt adhesive 5, even without compounding,shows an optimum combination of properties for the application (FIG. 1).

What is claimed is:
 1. A ready-to-use hotmelt adhesive comprising atleast 95 wt % of one or more polyolefin copolymer waxes produced usingmetallocene catalysts, wherein the polyolefin copolymer wax consists ofpropylene and one or more further monomers selected from the groupconsisting of ethylene and branched or unbranched 1-alkenes having 4 to20 carbon atoms and comprises units of propylene and ethylene, where theamount of structural units originating from the propylene in thecopolymer wax is between 85 and 95 wt %, wherein the polyolefincopolymer wax has a number-average molar mass M_(n) in the range of15,000 and 25,000 g/mol and a weight-average molar mass M_(w) in therange of 25,000 and 35,000 g/mol, a dropping point or ring and ballsoftening point in the range of 100 and 120° C., a heat of fusion of notmore than 60 J/g, a melt viscosity, measured at a temperature of 170°C., of 8,000 to 15,000 mPa·s, and a glass transition temperature of notmore than −15° C., and wherein the hotmelt adhesive has a melt surfacetension, measured at a temperature of 170° C., of not more than 23 mN/m,wherein the hotmelt adhesive has an entropy-elastic temperature rangeΔT_(entropy-el)(tan δ), measured as the difference from glass transitiontemperature Tg(tan δ_(max)) from loss factor and softening temperature(onset of the loss modulus tan δ_(onset)) of 80 to 110° C.
 2. Theready-to-use hotmelt adhesive as claimed in claim 1, wherein thepolyolefin copolymer wax or waxes have a heat of fusion in the range of40 to 60 J/g, a melt viscosity, measured at a temperature of 170° C., ofbetween 8,000 and 11,000 mPa·s, and a glass transition temperature ofnot more than −20° C.
 3. The ready-to-use hotmelt adhesive as claimed inclaim 1, which is produced directly in the polymerization reactorwithout further compounding and, when two or more different polyolefinwaxes are used, is produced as a reactor blend.
 4. The ready-to-usehotmelt adhesive as claimed in claim 1, which further comprises one ormore substances selected from the group consisting of polyolefinpolymers, resins, waxes, plasticizers, polar or apolar polymers,pigments, fillers, stabilizers, and antioxidants in additive amounts. 5.The ready-to-use hotmelt adhesive as claimed in claim 1, employed as abinder for the production of traffic markings.